The convergence of the mobile telephone network, the static telephone network, and the IP network provides a myriad of communication options for users. If one seeks to contact another individual, he or she may do so by electronic mail or e-mail, instant messaging, wired or wireless telephone, personal computer, pager, personal digital assistant or PDA, and Unified Messaging or UM systems, to name but a few. With so many options, it is difficult, if not impossible, to determine which option at a given point in time will provide the caller with the highest likelihood of contacting the desired individual or callee. Trial and error and guesswork are the typical techniques used to contact the callee, which more often than not leads to a waste of time and frustration on the part of the caller.
Various attempts have been made to provide a presence and availability system that can track temporally a person's presence and availability and thereby provide a contactor with the highest likelihood of contacting the person. This is typically effected by collecting information from communication devices associated with the person. Such systems can further permit the person to define their availability to be contacted generally and/or to defined groups of contactors and how that contactor or group of contactors may contact them. This can be effected by allowing the person to configure the contactor's access control settings. As will be appreciated, contactors can view the information regarding the availability of contactees and use that information to determine whether or not and how to initiate or continue communications.
Recently, the Session Initiation Protocol or SIP (which is a simple signaling/application layer protocol for data network multimedia conferencing and telephony) has been developed to facilitate media-independent signaling and the implementation of presence and availability systems. Although other protocols may be equally supportive of presence concepts, SIP provides an illustrative basis for the present invention. In SIP, end systems and proxy servers can provide services such as call forwarding, contactee and contactor number delivery (where numbers can be any naming scheme such as a conventional URL format), personal mobility (the ability to reach a contactee under a single, location-independent address even when the contactee changes terminals), terminal-type negotiation and selection (e.g., a contactor can be given a choice on how to reach the contactee), terminal capability negotiation, caller and callee authentication, blind and supervised call transfer, and invitations to multiparty conferences.
To provide these varied services, SIP uses a relatively simple message system. Contacts begin via an “INVITE” message (with the contactor's codec preferences) and an “OK” message (with the contactee's codec preferences). Various software entities may participate, namely registrars which maintain a map of the addresses of a given user at the current time, proxies which perform call routing, some session management, user authentication, redirect functions, and routing to media gateways, redirect servers which perform a subset of forwarding functions, and SIP location servers which maintain user profiles and provide subscriber registration. “Registration” is a mechanism whereby a user's communication device registers with the network each time he or she comes online or needs to charge existing registration and individual profiles are maintained that specify information for routing contacts based on a number of different criteria.
Notwithstanding the above, conventional presence and availability systems are limited in scope. Conventional presence and availability systems have been tied to a small subset of Universal Resource Identifier (URI) (or Universal Resource Locator (URL)) name spaces and few non-URI or non-URL name spaces, particularly with respect to object identification systems not associated with an individual. As used herein, a “name space” refers to a numeric, alphabetical, or alpha-numeric-based system or address that is controlled by an entity or standards so as to maintain the attribute of identifier uniqueness within a predefined set of identifiers. Examples of name spaces not supported by current presence systems include Universal Product Codes or UPC 's, GPS locaton data, ISBN codes, and proprietary messaging handles. An address in a name space may be associated with one or more communication devices or objects. Interfacing presence and availability systems to these other communications and identification systems is important in view of the increasing degree of convergence of conventional telephony, the Internet, and other systems. Moreover, conventional presence and availability systems are not inter-networked with other external presence and availability systems and/or other systems collecting useful presence-related information, such as the subscriber physical location information generated by wireless networks. Although some related work is being done in the Internet Engineering Task Force or IETF on open presence systems using work done in the SIMPLE, IMPP and SIP working groups, the current proposals address only the basic frameworks of a presence service and not name space inter-working beyond E.164 systems. Existing practice and standards still lack many algorithms and techniques important to meeting the needs of working, interoperable presence and availability systems.